Optical device for indicating correct operating speed of phonograph turntables



April 8, I94 M. R. MAUSSHARDT 5 OPTICAL DEVICE FOR INDICATING CORRECT OPERATING SPEED OF A PHQNUGRAPH TURNTABLE Filed Aug. 28, 1944 INVENTOR Mmou a. mussrmnar.

ATTORNEY Patented Apr. 8, 1947 UNITED STATES PATENT OFFICE OPTICAL DEVICE FOR INDICATING COR- RECT ()PERATING SPEED OF PHONO- GRAPH TURNTABLES 1 Claim.

This invention is a speed indicator or gauge for phonographs, by means of which an operator of the phonograph may be visually apprised that the speed of rotation of the turntable is not less than that required for proper reproduction of the record being played.

The invention comprehends a visual gauge or indicator to be applied to phonograph records and of such character that when the turntable has reached a speed of rotation suitable for proper reproduction of the record the gauge or indicator presents a band of predetermined color or density.

A further object is to provide a device for the purpose which may be made as a separate element adapted to be associated with any record being played as may be desired.

Fig. 1 on the drawing is a top plan view of the device.

Fig. 2 is an edge view of the same.

Referring to the numerals of reference on the drawings, the device comprises a 1abel of circular disc form of thin cardboard or the like and gummed on its underside for attachment to a phonograph record. The disc is provided with a central hole 2 to coincide with that in the record, so that the disc may be properly disposed centrally of the record.

The disc I is provided with a peripheral dark colored band 4 (preferably black for good contrast) with distinctive radial bars 3 across the band intermediate its outer and inner peripheries. These bars are preferably colored white and are of a length slightly less than the width of said band.

When the disk is attached to a record and the latter is rotated, the bars 3 will appear to the eye as a continuous substantially gray annular band bordered by concentric bands of a darker color if the speed of the record is not less than that required for a proper reproduction of the record.

I claim:

A speed indicator of the character described comprising a circular disk-like body having a central opening therein so positioned to coincide with the central opening of a disk containing a sound track, and an adhesive on the underside of said body, the top surface of said body having a circular band of dark color thereon concentric with said opening, said band being interrupted. by a circular series of radially disposed bars of a lighter contrasting color, the length of the respective bars being less than the width of said band, so that during rotation of said disk at a predetermined minimum speed, said bars will assume the appearance of a lighter colored band superimposed upon and contrasting with said darker band.

MILTON R. MAUSSI-IARDT.

REFERENCES CITED The following references are of record in the file of this patent: 

